Defect repairing method and preparation method of N-type crystalline silicon battery

Abstract

The invention relates to a defect repairing method for an N-type crystalline silicon battery, which comprises the following steps of: detecting N-type crystalline silicon battery pieces, and screening out defective battery pieces with cross-like hidden cracks; the defective battery piece is subjected to pre-heating treatment, the pre-heating treatment temperature ranges from 270 DEG C to 310 DEG C, and the heat preservation time ranges from 330 s to 430 s; electric injection treatment is carried out, the electric injection treatment temperature ranges from 270 DEG C to 310 DEG C, the heat preservation time ranges from 2640 s to 3440 s, and the electric injection current ranges from 10 A to 12 A; and after cooling, repairing is completed. The invention also provides a preparation method of the N-type crystalline silicon cell. According to the defect repairing method of the N-type crystalline silicon cell, provided by the invention, under the condition that the cleanliness of a current factory cannot meet a higher requirement, only one step of electric injection treatment is added on the basis of an original preparation process of the N-type crystalline silicon cell, so that the cross-like hidden crack defect can be repaired in a targeted manner, and therefore, the yield of the N-type crystalline silicon cell can be effectively improved, and the production cost of the N-type crystalline silicon cell can be reduced. And the repairing method is simple and high in efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a defect repairing method of an N-type crystalline silicon cell and a preparation method thereof. Background Art

[0002] In recent years, with the advantages of N-type silicon wafers such as high minority carrier lifetime, high tolerance to metal contamination, and no photoinduced boron-oxygen degradation, more and more battery manufacturers choose to prepare high-efficiency crystalline silicon cells on N-type substrates, such as TOPCon cells, HJT cells, N-type BC cells, etc.

[0003] However, although the conversion efficiency of N-type crystalline silicon cells under the LPCVD route is higher than that of P-type, the yield is lower than that of PERC technology, mainly due to defects such as cross cracks. Existing studies have shown that the main reason for the cross crack defects is the adsorption of dust particles on the silicon wafer before boron diffusion. However, existing factories can no longer meet the requirements of higher cleanliness, making it difficult to avoid the cross crack defects in the process of preparing N-type crystalline silicon cells. Summary of the invention

[0004] Based on this, it is necessary to provide a defect repair method for an N-type crystalline silicon cell and a preparation method thereof to address the above problems. The defect repair method for an N-type crystalline silicon cell can specifically repair the cross-like hidden crack defects of the N-type crystalline silicon cell, and the repair method is simple and efficient, and can effectively improve the yield.

[0005] A defect repair method for an N-type crystalline silicon cell comprises the following steps:

[0006] Test N-type crystalline silicon cells and screen out defective cells with cross-like hidden cracks;

[0007] The defective battery cell is subjected to a pre-heating treatment, wherein the pre-heating treatment temperature is 270° C. to 310° C. and the heat preservation time is 330s to 430s;

[0008] Conducting an electric injection treatment, wherein the electric injection treatment temperature is 270° C. to 310° C., the heat preservation time is 2640s to 3440s, and the electric injection current is 10A to 12A;

[0009] After cooling, the repair is complete.

[0010] In one embodiment, the pre-heating treatment and the electrical injection treatment are both performed in a box stacking device.

[0011] In one embodiment, the box stacking device includes at least N workstations, N≥2, the pre-heating treatment step is performed at the first workstation of the box stacking device, and the electrical injection treatment step is performed continuously at the second to N workstations of the box stacking device.

[0012] In one embodiment, the box stacking device includes at least 9 workstations, the pre-heating treatment step is performed at the first workstation of the box stacking device, and the electrical injection treatment step is performed continuously at the second to ninth workstations of the box stacking device.

[0013] In one of the embodiments, during the steps of the pre-heating treatment and the electrical injection treatment, the temperature of the upper electrode in the cassette stacking device is less than or equal to the temperature of the lower electrode.

[0014] In one embodiment, in the step of pre-heating, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C;

[0015] And / or, in the step of electrical injection treatment, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C.

[0016] In one of the embodiments, the step of the electrical injection treatment is performed continuously at the 2nd to Nth stations of the box stacking device, and the electrical injection current of each station is the same.

[0017] In one of the embodiments, the step of the electrical injection treatment is performed continuously at the 2nd to Nth stations of the box stacking device, and the insulation time of each station is the same.

[0018] A method for preparing an N-type crystalline silicon battery comprises the following steps:

[0019] Preparation of N-type crystalline silicon cells;

[0020] Defective battery cells with cross-like hidden cracks are repaired according to the defect repair method.

[0021] In one embodiment, the N-type crystalline silicon cell is selected from an N-type TOPCon cell.

[0022] The defect repair method of N-type crystalline silicon cells provided by the present invention, after preparing N-type crystalline silicon cell slices, screens out defective cell slices with quasi-cross hidden cracks through testing, firstly performs a pre-heating treatment so that the hydrogen in the silicon nitride on the surface of the defective cell slice is in a relatively active state, which is convenient for enhancing passivation, and then, through continuous heating and current injection, the H with different valence states in the silicon nitride and aluminum oxide repairs the branches of the quasi-cross hidden cracks in the defective cell slice, thereby being able to specifically repair the quasi-cross hidden crack defects.

[0023] Therefore, when the current factory cleanliness cannot meet higher requirements, it is only necessary to add a step of electrical injection treatment on the basis of the original preparation process of N-type crystalline silicon cell to carry out targeted repair of cross-like hidden crack defects, thereby effectively improving the yield of N-type crystalline silicon cells. The repair method is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a comparison diagram before and after the repair of the cross-like hidden crack in Example 1;

[0026] Figure 2 This is a comparison diagram before and after the repair of the quasi-cross crack in Example 2;

[0027] Figure 3 This is a comparison diagram before and after the repair of the cross-like hidden crack of comparative example 1;

[0028] Figure 4 This is a comparison diagram before and after the repair of the cross-like hidden crack of comparative example 2;

[0029] Figure 5 This is a comparison diagram before and after the repair of the cross-like hidden cracks in comparative example 3. DETAILED DESCRIPTION

[0030] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0032] The present invention provides a defect repair method for an N-type crystalline silicon cell, comprising the following steps:

[0033] S1, testing N-type crystalline silicon cells to screen out defective cells with cross-like hidden cracks;

[0034] S2, pre-heating the defective battery cell, wherein the pre-heating temperature is 270° C. to 310° C., and the holding time is 330s to 430s;

[0035] S3, perform electric injection treatment, wherein the electric injection treatment temperature is 270°C to 310°C, the heat preservation time is 2640s to 3440s, and the electric injection current is 10A to 12A; after cooling, the repair is completed.

[0036] In step S1, electroluminescence and other equipment are used to detect N-type crystalline silicon cells, and defective cells with cross-like hidden cracks are screened out, and then steps S2 and S3 are used to repair them.

[0037] In the specific implementation process, the screened defective cells can be collected and put into a box-type stacking device for repair in step S2 and step S3. The number of cells that can be accommodated in the box-type stacking device is 300cps to 500cps, preferably 450cps. The upper end of the box-type stacking device is open, the lower end is not open, and both ends are provided with conductive metal plates used as upper and lower electrodes respectively, with a thickness of 1mm to 6mm. The defective cells are preheated by heating the upper and lower electrodes to a certain temperature, and the defective cells are electrically injected by energizing the upper and lower electrodes.

[0038] The cassette stacking device includes at least N stations, where N is greater than or equal to 2. In a specific implementation process, step S2 can be performed at the first station of the cassette stacking device, and then step S3 can be performed at the second to N stations, and steps S2 and S3 are performed continuously. For example, the cassette stacking device can be provided with 9 stations, wherein the first station is a pre-heating station, which sets the temperature but does not set the current. The pre-heating treatment is first performed through the station, so that the hydrogen in the silicon nitride on the surface of the defective battery cell is in a relatively active state, which is convenient for enhancing the passivation. Then, through continuous heating and current injection at the second to ninth stations, the H in different valence states in the silicon nitride and aluminum oxide repairs the branches of the cross-like hidden cracks in the defective battery cell, thereby being able to repair the cross-like hidden crack defects in a targeted manner.

[0039] Optionally, when step S2 is performed in a box stacking device, the temperature of the upper electrode is less than or equal to the temperature of the lower electrode. Preferably, the temperature difference between the upper electrode and the lower electrode is less than or equal to 40°C, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C. Further preferably, the temperature of the upper electrode is 280°C, the temperature of the lower electrode is 300°C, and the holding time is 330s to 430s. Preferably, the holding time is 380s.

[0040] Optionally, when step S3 is performed in a box stacking device, the temperature of the upper electrode is less than or equal to the temperature of the lower electrode. Preferably, the temperature difference between the upper electrode and the lower electrode is less than or equal to 40°C, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C. Further preferably, the temperature of the upper electrode is 280°C, and the temperature of the lower electrode is 300°C. In the specific implementation process, the insulation time of each station may be the same or different. Preferably, the electrical injection current of each station is the same, and / or the insulation time of each station is the same.

[0041] Optionally, the box-type stacking device further includes at least M cooling stations for cooling the battery cells after the electrical injection process, where M is greater than or equal to 1. In this case, the box-type stacking device includes N+M stations.

[0042] The present invention also provides a method for preparing an N-type crystalline silicon cell, comprising the following steps:

[0043] S1, preparing N-type crystalline silicon cells;

[0044] S2, repairing the defective battery cell with cross-like hidden cracks according to the above-mentioned defect repair method.

[0045] In step S1, the N-type crystalline silicon cell is selected from an N-type TOPCon cell, and the N-type TOPCon cell preparation steps include:

[0046] N-type TOPCon cells are obtained through texturing, boron diffusion, etching, tunneling layer preparation and polysilicon layer deposition, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, light injection or electrical injection.

[0047] In step S2, the prepared N-type TOPCon cells are subjected to efficiency testing and EL sorting to screen out defective cells with cross-like hidden cracks, and the defective cells with cross-like hidden cracks are repaired according to the above-mentioned defect repair method.

[0048] Based on the existing process for preparing N-type crystalline silicon cell pieces, the present invention screens out defective cell pieces with similar cross cracks through testing and repairs them in a targeted manner, thereby effectively improving the yield of N-type crystalline silicon cells, and the repair efficiency is high and the repair is highly targeted. In addition, since it is not necessary to repair all the prepared cell pieces, the workload is greatly reduced and the preparation efficiency of N-type crystalline silicon cells is improved.

[0049] Hereinafter, the defect repair method of the N-type crystalline silicon cell will be further described through the following specific embodiments.

[0050] Example 1

[0051] The N-type TOPCon cell is prepared, including: texturing, boron diffusion, etching, tunneling layer preparation and deposition of polysilicon layer, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, and light injection to obtain the N-type TOPCon cell.

[0052] The above-mentioned cells were tested using electroluminescent equipment to screen out defective cells with cross-like hidden cracks, and the defective cells were collected and placed in a box stacking device. After being filled with 450cps, the box stacking device was placed on the first station for pre-heating treatment, and then the electric injection treatment was carried out on the second to ninth stations in turn, and then the temperature was lowered at the tenth station to complete the repair. The conditions of each station are shown in Table 1:

[0053] Table 1

[0054] Workstation 1 2～9 10 Upper electrode temperature / ℃ 280 280 / Lower electrode temperature / ℃ 300 300 / Current / A 0 11 / Process time of each station / s 380 380 /

[0055] The repaired cells were tested again using electroluminescent equipment. The test results are as follows: Figure 1 As shown, a is the quasi-crossing hidden crack defect site before repair, and b is the quasi-crossing hidden crack defect site after repair. From the comparison between a and b, it can be seen that after the repair, the branches of the quasi-crossing hidden crack are repaired in a targeted manner, so that the quasi-crossing hidden crack defect is significantly improved.

[0056] Example 2

[0057] The N-type TOPCon cell is prepared, including: texturing, boron diffusion, etching, tunneling layer preparation and deposition of polysilicon layer, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, and light injection to obtain the N-type TOPCon cell.

[0058] The above cells were tested using electroluminescent equipment to screen out defective cells with cross-like hidden cracks, and the defective cells were collected and placed in a box stacking device. After being filled with 450cps, the box stacking device was placed on the first station for pre-heating treatment, and then the electric injection treatment was carried out on the second to ninth stations in turn, and then the temperature was lowered at the tenth station to complete the repair. The conditions of each station are shown in Table 2:

[0059] Table 2

[0060] Workstation 1 2～9 10 Upper electrode temperature / ℃ 270 270 / Lower electrode temperature / ℃ 290 290 / Current / A 0 11 / Process time of each station / s 340 340 /

[0061] The repaired cells were tested again using electroluminescent equipment. The test results are as follows: Figure 2 As shown, a is the quasi-crossing hidden crack defect site before repair, and b is the quasi-crossing hidden crack defect site after repair. From the comparison between a and b, it can be seen that after the repair, the branches of the quasi-crossing hidden crack are repaired in a targeted manner, so that the quasi-crossing hidden crack defect is significantly improved.

[0062] Example 3

[0063] The N-type TOPCon cell is prepared, including: texturing, boron diffusion, etching, tunneling layer preparation and deposition of polysilicon layer, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, and light injection to obtain the N-type TOPCon cell.

[0064] The above cells were tested using electroluminescent equipment to screen out defective cells with cross-like hidden cracks, and the defective cells were collected and placed in a box stacking device. After being filled with 450cps, the box stacking device was placed on the first station for pre-heating treatment, and then the electric injection treatment was carried out on the second to ninth stations in turn, and then the temperature was lowered at the tenth station to complete the repair. The conditions of each station are shown in Table 3:

[0065] Table 3

[0066] Workstation 1 2～9 10 Upper electrode temperature / ℃ 270 270 / Lower electrode temperature / ℃ 310 310 / Current / A 0 11 / Process time of each station / s 330 330 /

[0067] The repaired cells were tested again using electroluminescent equipment, and the branches of the quasi-cross cracks were repaired in a targeted manner, resulting in a significant improvement in the quasi-cross crack defects.

[0068] Example 4

[0069] The N-type TOPCon cell is prepared, including: texturing, boron diffusion, etching, tunneling layer preparation and deposition of polysilicon layer, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, and light injection to obtain the N-type TOPCon cell.

[0070] The above cells were tested using electroluminescent equipment to screen out defective cells with cross-like hidden cracks, and the defective cells were collected and placed in a box stacking device. After being filled with 450cps, the box stacking device was placed on the first station for pre-heating treatment, and then the electric injection treatment was carried out on the second to ninth stations in turn, and then the temperature was lowered at the tenth station to complete the repair. The conditions of each station are shown in Table 4:

[0071] Table 4

[0072] Workstation 1 2～9 10 Upper electrode temperature / ℃ 270 270 / Lower electrode temperature / ℃ 290 290 / Current / A 0 10 / Process time of each station / s 430 430 /

[0073] The repaired cells were tested again using electroluminescent equipment, and the branches of the quasi-cross cracks were repaired in a targeted manner, resulting in a significant improvement in the quasi-cross crack defects.

[0074] Example 5

[0075] The N-type TOPCon cell is prepared, including: texturing, boron diffusion, etching, tunneling layer preparation and deposition of polysilicon layer, phosphorus doping and oxidation, de-coating, cleaning, coating, screen printing, sintering, and light injection to obtain the N-type TOPCon cell.

[0076] The above cells were tested using electroluminescent equipment to screen out defective cells with cross-like hidden cracks, and the defective cells were collected and placed in a box stacking device. After being filled with 450cps, the box stacking device was placed on the first station for pre-heating treatment, and then the electric injection treatment was carried out on the second to ninth stations in turn, and then the temperature was lowered at the tenth station to complete the repair. The conditions of each station are shown in Table 5:

[0077] Table 5

[0078] Workstation 1 2～9 10 Upper electrode temperature / ℃ 290 290 / Lower electrode temperature / ℃ 310 310 / Current / A 0 12 / Process time of each station / s 330 330 /

[0079] The repaired cells were tested again using electroluminescent equipment, and the branches of the quasi-cross cracks were repaired in a targeted manner, resulting in a significant improvement in the quasi-cross crack defects.

[0080] Comparative Example 1

[0081] The difference between Comparative Example 1 and Example 1 is that during the pre-heating process, a current of 11A is injected. The conditions of each station are shown in Table 6:

[0082] Table 6

[0083] Workstation 1 2～9 10 Upper electrode temperature / ℃ 280 280 / Lower electrode temperature / ℃ 300 300 / Current / A 11 11 / Process time of each station / s 380 380 /

[0084] The repaired cells were tested again using electroluminescent equipment. The test results are as follows: Figure 3 As shown, a is the quasi-crossing hidden crack defect site before repair, and b is the quasi-crossing hidden crack defect site after repair. From the comparison between a and b, it can be seen that there is no obvious difference in the branches of the quasi-crossing hidden cracks before and after repair, and the quasi-crossing hidden crack defect has not been significantly improved.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 1 is that there is no pre-heating process, and the conditions of each station are shown in Table 7:

[0087] Table 7

[0088] Workstation 1 2～9 10 Upper electrode temperature / ℃ / 280 / Lower electrode temperature / ℃ / 300 / Current / A / 11 / Process time of each station / s / 380 /

[0089] The repaired cells were tested again using electroluminescent equipment. The test results are as follows: Figure 4 As shown, a is the quasi-crossing hidden crack defect site before repair, and b is the quasi-crossing hidden crack defect site after repair. From the comparison between a and b, it can be seen that there is no obvious difference in the branches of the quasi-crossing hidden cracks before and after repair, and the quasi-crossing hidden crack defect has not been significantly improved.

[0090] Comparative Example 3

[0091] The difference between Comparative Example 3 and Example 1 is that 8A current is injected into stations 2 to 5, and 12A current is injected into stations 6 to 9. The conditions of each station are shown in Table 8:

[0092] Table 8

[0093] Workstation 1 2～5 6～9 10 Upper electrode temperature / ℃ 280 280 280 / Lower electrode temperature / ℃ 300 300 300 / Current / A 0 8 12 / Process time of each station / s 380 380 380 /

[0094] The repaired cells were tested again using electroluminescent equipment. The test results are as follows: Figure 5 As shown, a is the quasi-crossing hidden crack defect site before repair, and b is the quasi-crossing hidden crack defect site after repair. From the comparison between a and b, it can be seen that there is no obvious difference in the branches of the quasi-crossing hidden cracks before and after repair, and the quasi-crossing hidden crack defect has not been significantly improved.

[0095] Comparative Example 4

[0096] The difference between Comparative Example 4 and Example 1 is that 12A current is injected into stations 2 to 5, and 8A current is injected into stations 6 to 9. The conditions of each station are shown in Table 9:

[0097] Table 9

[0098] Workstation 1 2～5 6～9 10 Upper electrode temperature / ℃ 280 280 280 / Lower electrode temperature / ℃ 300 300 300 / Current / A 0 12 8 / Process time of each station / s 380 380 380 /

[0099] The repaired cells were tested again using electroluminescent equipment. There was no obvious difference in the branches of the quasi-cross cracks before and after the repair, and the quasi-cross crack defects were not significantly improved.

[0100] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A defect repair method for an N-type crystalline silicon cell, characterized in that: The following steps are involved: Test N-type crystalline silicon cells and screen out defective cells with cross-like hidden cracks; The defective battery cell is subjected to a pre-heating treatment, wherein the pre-heating treatment temperature is 270° C. to 310° C. and the heat preservation time is 330s to 430s; Conducting an electric injection treatment, wherein the electric injection treatment temperature is 270° C. to 310° C., the heat preservation time is 2640s to 3440s, and the electric injection current is 10A to 12A; After cooling, the repair is complete.

2. The defect repair method of N-type crystalline silicon cell according to claim 1, characterized in that: The steps of the pre-heating treatment and the electric injection treatment are both performed in a box-type stacking device.

3. The defect repair method of N-type crystalline silicon cell according to claim 2, characterized in that: The box stacking device comprises at least N workstations, N≥2, the preheating treatment step is performed at the first workstation of the box stacking device, and the electrical injection treatment step is performed continuously at the second to N workstations of the box stacking device.

4. The defect repair method of an N-type crystalline silicon cell according to claim 3, characterized in that: The cassette stacking device comprises at least 9 workstations, the pre-heating treatment step is performed at the first workstation of the cassette stacking device, and the electrical injection treatment step is performed continuously at the second to ninth workstations of the cassette stacking device.

5. The defect repair method of N-type crystalline silicon cell according to claim 2, characterized in that: In the steps of the pre-temperature increase treatment and the electric injection treatment, the temperature of the upper electrode in the cassette stacking device is less than or equal to the temperature of the lower electrode.

6. The defect repair method of N-type crystalline silicon cell according to claim 5, characterized in that: In the step of preheating, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C; And / or, in the step of electrical injection treatment, the temperature of the upper electrode is 270°C to 290°C, and the temperature of the lower electrode is 290°C to 310°C.

7. The defect repair method of an N-type crystalline silicon cell according to claim 3 or 4, characterized in that: The steps of the electric injection treatment are performed continuously at the 2nd to Nth stations of the box stacking device, and the electric injection current of each station is the same.

8. The defect repair method of an N-type crystalline silicon cell according to claim 3 or 4, characterized in that: The steps of the electrical injection treatment are performed continuously at the 2nd to Nth stations of the cassette stacking device, and the heat preservation time of each station is the same.

9. A method for preparing an N-type crystalline silicon battery, characterized in that: The following steps are involved: Preparation of N-type crystalline silicon cells; Defect repair is performed on a defective battery cell having cross-like hidden cracks according to the defect repair method as described in any one of claims 1 to 8.

10. The method for preparing an N-type crystalline silicon cell according to claim 9, characterized in that: The N-type crystalline silicon cell is selected from an N-type TOPCon cell.

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